4.140/MAS.863

Where Emilee Johnson Tries to Make Almost Anything

Input Week

This week we had to level up our electronics experience a bit from what we've been doing in previous weeks by creating a board that senses something. I actually chose to modify my board from week 5 instead of creating something completely new by scratch, because it was relatively trivial to add the photo resistor to what I already had. I used the class examples as far as where to throw things for the circuit, and then I had an open analog input pin to use so I just tied the resistor in there. One thing that was annoying I suppose was ripping up all the traces around where I decided to put it and having to rewire everything, which was already a tedious project the last time I did it. I learned this week that I need to stop forgetting I can run wires through the middle of pads on things like capacitors and resistors. Super useful in that it generates a lot of routes but prior to this point I've just been dumb and have tried to go around everything each time. It took a lot of playing around but ultimately I wound up with something that meets all of the design rules. I was really trying to modify the previous board as little as possible, which resulted in a very crowded board.

Project 09a
Here's the schematic of the modified board. Really the only difference between this one and my week 5 board is the photo resistor on the bottom. Nothing particularly exciting to see here.
Project 09b
Eagle diagram of the board itself. Slightly more exciting than the schematic. Lost the toilet humour from the last board to this one. As you can see I had to reorient the resistor and modified some of my original traces to fit everything into the tight space. It supposedly is meeting all the design rules....we'll see how things play out. I can tell just from looking at it that it's going to be super tedious to stuff this board and I hope that I have good enough hands to manage it. I think the order by which I solder things is going to be important because as components go on I will be limiting myself in space. Right now I'm planning on first putting the micro-controller on, and then probably starting at the cramped corner and working my way diagonally across.
Project 09c
Modela milled product. Nothing too exciting here. Traces turned out so that's good. Ready to be stuffed and programmed. Kind of wish I'd read ahead and just put a sensor on the first week we did electronics design, so that all I had to do was worry about actually programming it, but you know what they say about hindsight. It's always good practice to make another one.
Project 09d
Stuffed board, ready for programming. I've worked with this type of sensor before in 2.678 as well as 6.01, although I don't think either time they were surface mount components (not that it makes too much of a difference). It's been a while since I used python to communicate and I don't really know how to get the serial read from it, so I'm definitely looking to Arduino this week to bail me out. In 2.678 there's a project you work on towards the end of term where you construct a small robotic car that senses light on a track to autonomously drive itself around. If I have time I might like to recreate that project next week and translate this serial input into a servo output, but I'm also thinking about how I might want to change my final project so if I can experiment with concepts for that then I'll probably pass on the neat little robotic car.